1. Field of the Invention
The present invention relates to a capacitor using a solid electrolyte, a capacitor-embedded board, and a method for manufacturing the capacitor.
2. Description of the Related Art
A capacitor using a solid electrolyte has a structure in which at least a first electrode, a dielectric layer, an organic solid electrolyte, and a second electrode are stacked in this order. Such a capacitor is generally manufactured in the following manner. On the surface of an anode serving as the first electrode, a dielectric layer is formed with an anodic oxidation method, or the like. Then, an organic solid electrolyte layer is formed. Thereafter, on the surface of the organic solid electrolyte layer, a carbon paste, a silver paste, or the like is coated, thereby to form a cathode as the second electrode such as disclosed in JP-64-32621.
Herein, when an electrolytically polymerized film of polypyrrole is used as the solid electrolyte layer, a thin manganese dioxide film or a thin chemically polymerized polypyrrole layer is formed on the surface of the dielectric layer. Thus, conductivity is imparted to the surface of the dielectric layer, followed by electrolytic polymerization.
However, a conventional capacitor has the following problem. An organic solid electrolyte layer is stacked on the surface of an inorganic layer such as a dielectric layer or a manganese dioxide layer. For this reason, when a temperature change occurs, a stress caused by the difference between the thermal expansion coefficient of the organic solid electrolyte layer and the thermal expansion coefficient of the inorganic layer occurs. As a result, the organic solid electrolyte layer peels off therefrom.